Device and method for fixation for bone or soft tissue deformity of digits

ABSTRACT

A fixation device comprises a first clamping member having an adjustable clamping collar and a first curved support portion attached to the adjustable clamping collar. The first clamping member is adapted to receive a digit. The first curved support portion is adapted to support an inferior surface of a proximal phalanx of the digit. A distal member is adjustably attachable to the first clamping member. The distal member has a second curved support surface adapted to support an inferior surface of a distal phalanx of the digit and a curved distal end adapted to apply a compressive force in a proximal direction to a distal end of the distal phalanx.

This application claims the benefit of U.S. provisional application No.61/746,426, filed on Dec. 27, 2012, the entirety of which isincorporated herein by reference.

FIELD

This disclosure relates to medical devices.

BACKGROUND

Fingers and toes may become deformed. A hammertoe is a deformity of thetissues surrounding the bony structures of the lesser toes. Thepatient's toes elevate and cause discomfort while wearing shoes. Forexample, poorly fitting shoes can cause a hammertoe deformity of theproximal interphalangeal (PIP) joint of any of the lesser toes causingit to be permanently bent. Osteoarthritis, rheumatoid arthritis, stroke,Charcot-Marie-Tooth disease or diabetes may cause muscle, nerve, orjoint damage which may also deform one or more joints.

Depending on the degree of deformity and the patient's history, a doctormay determine that fixation of the affected digit is appropriate tocorrect the deformity. For example, Wright Medical Technologies ofArlington, Tenn. provides the “PRO-TOE”® line of bone implants forcorrecting a hammertoe deformity. A threaded member has a longitudinalaxis and threads extending from the proximal end to the distal end. Atoothed blade is integrally attached to the distal end of the threadedmember. The blade extends in a radial direction away from thelongitudinal axis. The blade has an outer edge with a plurality of teethon it.

Improved fixation devices and methods are desired for correcting jointdeformities, such as hammertoe and the like.

SUMMARY

In some embodiments, a fixation device comprises a first clamping memberhaving an adjustable clamping collar and a first curved support portionattached to the adjustable clamping collar. The first clamping member isadapted to receive a digit therethrough. The first curved supportportion is adapted to support an inferior surface of a proximal phalanxof the digit. A distal member is adjustably attachable to the firstclamping member. The distal member has a second curved support surfaceadapted to support an inferior surface of a distal phalanx of the digitand a curved distal end adapted to apply a compressive force in aproximal direction to a distal end of the distal phalanx.

In some embodiments, a fixation device comprises a proximal clampingmember and a distal clamping member. Each of the proximal and distalclamping members has an adjustable clamping collar adapted to receive adigit therethrough. First and second coaxial helical members areprovided, opposing each other. Each of the helical members has arespective proximal end fixedly attached to the proximal clamping memberand a respective distal end fixedly attached to the distal clampingmember.

In some embodiments, a fixation device comprises a proximal clampingmember and a distal clamping member. Each of the proximal and distalclamping members has an adjustable clamping collar adapted to receive adigit therethrough. A plurality of longitudinal spacers each have aproximal end attached to the proximal clamping member and a distal endattached to the distal clamping member. A plurality of spring membershave a proximal end attached to the proximal clamping member and adistal end attached to the distal clamping member. Each spring member islocated adjacent to and radially inward from a respective longitudinalspacer. Each longitudinal spacer constrains its respective spring memberto bow radially inwards.

In some embodiments, a fixation device comprises a tube comprising acontractible tubular woven mesh configured to contract radially underlongitudinal tension. At least one helical yarn or fiber is fastened ator near a first end of the tube and woven helically through the mesh andextends from a second end of the tube opposite the first end of thetube, such that the yarn is capable of applying radial compression tothe tube when placed under tension.

In some embodiments, a fixation device comprises a tube comprising acontractible tubular woven mesh configured to contract radially underlongitudinal tension. A plurality of sleeves are arranged around anouter surface of the tube, the sleeves smaller in diameter than thetube. At least one rib is removably insertable in at least a respectiveone of the plurality of sleeves. The at least one rib is formed of amaterial that is more rigid than a material of the tubular woven mesh.

In some embodiments, a bone implant comprises a helical threaded memberhaving first and second ends and a longitudinal central openingextending from the first end to the second end. The longitudinal centralopening has a longitudinal axis. At least one blade is integrallyattached to the first end of the helical threaded member. The bladeextends in a radial direction away from the longitudinal axis. The bladehas an outer edge with a plurality of teeth thereon.

In some embodiments, a bone implant comprises a central shaft havingfirst and second ends and a longitudinal axis. A first set of blades areintegrally attached to the first end of the central shaft. The first setof blades extend in a radial direction away from the central shaft. Eachof the first set of blades having an outer edge with a plurality ofteeth thereon. A second set of blades are integrally attached to thesecond end of the central shaft. The second set of blades extend in theradial direction away from the central shaft. Each of the second set ofblades has an outer edge with a plurality of teeth thereon. The secondset of blades are rotationally offset from the first set of blades.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side perspective view of an external fixation/correctiondevice formed in accordance with an embodiment of the invention for usein correcting deformities in a toe or finger;

FIG. 2 is a perspective exploded view of the externalfixation/correction device shown in FIG. 1;

FIG. 3 is a perspective view of the external fixation/correction deviceshown in FIGS. 1 and 2 with a superior member engage with remainder ofthe device;

FIG. 4 is a perspective view of an alternative embodiment of externalfixation/correction device including a strap or band woven through slotsin the clamping member;

FIG. 5 is a side perspective view of a second embodiment of externalfixation/correction device for use in correcting deformities of a toe orfinger;

FIG. 6 is a perspective view of a third embodiment of externalfixation/correction device for use in correcting deformities of the toeor finger;

FIG. 7 is a side elevational view of the external fixation/correctiondevice shown in FIG. 6, with a broken away, partially phantom fingerpositioned within the device;

FIG. 8 is a side elevational view of the external fixation/correctiondevice shown in FIG. 7;

FIG. 9 is a broken away, enlarged view of a portion of the externalfixation/correction device shown in FIGS. 6, 7 and 8;

FIG. 10 is a broken away, perspective view of the externalfixation/correction device shown in FIGS. 7, 8 and 9;

FIG. 11 is a perspective view, partially in phantom, of a drill guidesuitable for use with the fixation/correction devices shown in FIGS.1-10;

FIG. 11A is a broken away, detailed view of an adjustment mechanism forthe drill guide shown in FIG. 11;

FIG. 11B is a further broken away detail of another adjustment mechanismfor the drill guide shown in FIG. 11;

FIG. 12 is a side elevational view, partially in phantom, of yet afurther embodiment of external fixation/correction device for correctionof deformities in a toe or finger;

FIG. 13 is a cross sectional view taken along line 13-13 in FIG. 12;

FIG. 14 is a side perspective view, partially in phantom, of thefixation/correction devices shown in FIGS. 12-13;

FIG. 15 is a cross sectional view, taken along the lines 15-15, in FIG.14;

FIG. 15A is a perspective view of an alternative embodiment of externalfixation/correction device including helical yarn or fiber that arewoven into a tubular mesh;

FIG. 15B is a side elevational view of the external fixation/correctiondevice shown in FIG. 15A;

FIG. 15C is a side elevational view of the external fixation/correctiondevice shown in FIGS. 15A and 15B;

FIG. 16 is a perspective view of a bone implant, formed in accordancewith the invention used for correcting deformities of a toe or a finger;

FIG. 17 is a side elevational view of the bone implant shown in FIG. 16;

FIG. 18 is a further side perspective view of the bone implant shown inFIGS. 16 and 17;

FIG. 19 is a side elevational view of the bone implant shown in FIG. 18,showing the compliance of a helical threaded member;

FIG. 20 is a perspective view of an alternative embodiment of boneimplant formed in accordance with the invention;

FIG. 21 is a perspective view of yet another embodiment of bone implant,including a multiple barbed end;

FIG. 22 is a perspective view of a further embodiment of bone implantformed in accordance with the invention, including an alternativemultiple barb portion;

FIG. 23 is a perspective view of the bone implant shown in FIG. 22;

FIG. 24 is a cross sectional view of the bone implant shown in FIG. 23is taken along lines 24-24;

FIG. 25 is a perspective view of a proximal bone that has beenpre-drilled to receive a K wire in accordance with one method of theinvention;

FIG. 26 is a perspective view of a proximal bone shown in FIG. 25illustrating a physician drilling distally through a middle phalanx;

FIG. 27 is a perspective view showing a K wire exposed with a drillattached to the distal end of the K wire;

FIG. 28 is a side elevational view, partially in perspective, of aproximal phalanx having a helical threaded portion of a bone implantfully seated;

FIG. 29 is a perspective view, similar to FIG. 28, showing K wire fullyseated within the bone implant and proximal phalanx;

FIG. 30 is a side elevational view of a bone implant in accordance witha further embodiment of the invention;

FIG. 31 is an end view of the bone implant shown in FIG. 30;

FIG. 32 is a further end view of the bone implant shown in FIG. 30;

FIG. 33 is an exploded, partially perspective view of a set of phalangeshaving a bone implant lodged within a portion; and

FIG. 34 is a side elevational view, partially in phantom partially inperspective, showing the bone implant of FIG. 33 fully assembled withinthe proximal and distal phalanges.

DETAILED DESCRIPTION

This description of the exemplary embodiments is intended to be read inconnection with the accompanying drawings, which are to be consideredpart of the entire written description. In the description, relativeterms such as “lower,” “upper,” “horizontal,” “vertical,”, “above,”“below,” “up,” “down,” “top” and “bottom” as well as derivative thereof(e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should beconstrued to refer to the orientation as then described or as shown inthe drawing under discussion. These relative terms are for convenienceof description and do not require that the apparatus be constructed oroperated in a particular orientation. Terms concerning attachments,coupling and the like, such as “connected” and “interconnected,” referto a relationship wherein structures are secured or attached to oneanother either directly or indirectly through intervening structures, aswell as both movable or rigid attachments or relationships, unlessexpressly described otherwise.

FIGS. 1 to 3 show an embodiment of an external fixation device 100. FIG.2 is an exploded view. FIG. 3 shows the assembled device. Once assembledand applied to a digit (e.g., toe), the device 100 achieves axialcompression, radial compression and superior/inferior stabilization. Thedevice 100 can be used by itself for non-invasive treatment, or as afixation and support device during recovery from a surgical procedure.FIG. 1 shows the assembled device in use for correcting a hammertoedeformity.

The device 100 has a proximal first clamping member 110 having anadjustable clamping collar 112 and a first curved support portion 114attached to the adjustable clamping collar 112. The first clampingmember 110 is adapted to receive a digit 170 (e.g., a toe or finger)therethrough. The first curved support portion 114 is adapted to supportan inferior surface of a proximal phalanx 171 of the digit 170. Thecircular clamping collar 112 allows for radial compression on theproximal side of the joint-line. The collar 112 as shown has a ratchetmechanism with ramped teeth which permit tightening, but retain theclamp in position once tightened.

Although FIG. 1 shows ratchet type clamping collar 112, other clampingcollars can be used. For example, some embodiments include a clampingmechanism of a type used in cable ties. Some embodiments include a hookand locking latch type clamping collar. Some embodiments include a wormdrive clamping mechanism (similar to the drive of a hose clamp). Otherembodiments include circular springs of various configurations, whichthe doctor can pinch to expand, and which are biased to contract andprovide compression upon release. Other embodiments include hook andloop fasteners on ends of a band encircling the clamping collar 112.These are only examples of clamping mechanisms, and other embodimentsinclude other types of clamping mechanisms.

A distal member 130 is adjustably attachable to the first clampingmember 110. The distal member 130 has a second curved support surface132 adapted to support the inferior surface of a distal phalanx of thedigit 170 and a curved distal end 134 adapted to apply a compressiveforce in a proximal direction to a distal end of the distal phalanx 172.

In some embodiments, the distal member 130 has a hemispherical distalsurface which is sized and shaped to receive the most distal end of adigit (toe or finger). In some embodiments, the superior member hascantilever arms 153, each having a locking tab 154 adapted to mate withthe respective slot 116 of the clamping member 110.

An superior member 150 is configured to be attached to the firstclamping member 110 and the distal member 130. The superior member 150has a curved surface 152 adapted to apply a force against a superiorsurface of the digit 170. When the joint is flexed, the superior member150 assists in correcting that flex. In some embodiments, the superiormember 150 has spring-like material properties, a circular profile, andtabs 154, which interlock with slots 116 in both the clamping member 110and distal member 130. Some embodiments include a plurality of lockingtabs 154 or a plurality of slots 116 inferiorly, to allow incrementalincrease of compression. Each respective slot 116 is configured toreceive the at least one tab 154 with the superior member 150 at arespectively different location relative to the proximal member 110 &distal member 130, for applying a respectively different compressiveforce in the inferior direction. For example, in the embodiment of FIG.1, clamping member 110 has two slots 116, and superior member 150 hastab 154.

The superior member has means for locking the superior member to thefirst clamping member and the distal member. In some embodiments, thesuperior member 150 has one of the group consisting of a slot 116 and alocking tab 154, either of which provides a locking means. At least oneof the first clamping member 110 and the distal member 130 has the otherof the group consisting of a slot 116 and a locking tab 154 for engagingthe slot or locking tab of the superior member. For example, in theembodiment of FIG. 1, clamping member 110 and distal member 130 eachhave a slot 116, and superior member 150 has locking tab 154. In analternative embodiment, the superior member 150 has slots, and theclamping member 110 and distal member 130 each have a locking tab formating with the slots of the superior member 150. In another embodiment,the superior member has a slot at one end and tab at the other end; oneof the clamping member 110 and the distal member 130 has a tab and theother has a slot, for mating with the respective slot and tab of thesuperior member 150.

In some embodiments, the clamping member 110, distal member 130 andsuperior member 150 are made of padded stainless or titanium alloy.

In some embodiments, one of the first clamping member 110 and the distalmember 130 includes at least one locking tab 136, and the other of thefirst clamping member 110 and the distal member 130 includes a pluralityof slots 118, 119. Each respective slot 118, 119 is configured toreceive the at least one locking tab 136 with the distal member 130 at arespectively different location relative to the proximal member 110, forapplying a respectively different compressive force in the proximaldirection. For example, in the embodiment of FIG. 1, clamping member 110has two slots 118 and 119, and distal member 130 has locking tab 136. Insome embodiments, the locking tab 136 has ramped surface for easyinsertion, and for retaining the distal member 130 in position relativeto the clamping member 110, absent an affirmative user action to releasethe tab 136 from the slot 118 or 119.

In some embodiments, the slots 116 are substantially longer than thewidth of tabs 154, so that the superior member 150 can move along thelongitudinal (proximal-distal) axis. This allows the selection of slot118 or 119 to determine the engagement depth of the distal member 130relative to the clamping member 110, for control of the compressionforce against the distal end 172 of the digit 170.

An exemplary method of using the device 100 is as follows:

1. The user secures the device 100 to the proximal side 171 of thejoint, using the adjustable clamping collar 112 on the clamping member110.

2. The user assembles the distal member 130 to the clamping member 110by engaging the tabs 154 of the cantilever arms 153 into the slots 116of the clamping member 110.

a. The engagement depth of the tabs 136 determines the amount of axialcompression. Various engagement depth options are provided with multipleslots. The embodiment of FIG. 1 has two slots 118, 119, providing twoengagement depth options. Other embodiments include other numbers ofslots for this purpose (e.g., one, three, four or the like).

3. The user assembles the superior member 150 to the clamping member 110and distal member 130 by compressing the tabs 154 of the superior member150 inward and aligning the tabs 154 with the mating slots 116 of theclamping member 110 and distal member 130.

a. The amount of superior compression is determined by the matingfeatures selected (overlapping in the superior I inferior axis byselection of one of the slots 116), the degree of semi-circularity(i.e., the angle of the sector of a cylinder that the superior member150 subtends), as well as the material properties of the superior member150.

FIG. 4 shows another embodiment of a fixation device 200. A firstclamping member 210 has an adjustable clamping collar (not shown) at itsproximal end and a first curved support portion 214 attached to theadjustable clamping collar. The device 200 of FIG. 4 can include anytype of clamp 112 described above with respect to the device 100 ofFIGS. 1-3, and solely for brevity, descriptions thereof are notrepeated. The first clamping member 210 is adapted to receive a digit(not shown). The first curved support portion 214 is adapted to supportthe inferior surface of a proximal phalanx of the digit. A distal member230 is adjustably attachable to the first clamping member 210. Thedistal member 230 has a second curved support surface 232 adapted tosupport an inferior surface of a distal phalanx of the digit and acurved distal end 234 adapted to apply a compressive force in a proximaldirection to a distal end of the distal phalanx. A superior member 250is configured to be attached to the first clamping member 210 and thedistal member 230. The superior member 250 has a curved surface 252adapted to apply a force against a superior surface of the digit.

The device 200 of FIG. 4 differs from the embodiment of FIGS. 1-3 inthat it has a different means for locking the superior member to thefirst clamping member and the distal member. Device 200 has a fullyadjustable locking means including at least one suture, strap or band220 on each side (medial and lateral) of the device 200. The at leastone suture, strap or band 220 is formed of a strong, flexible material,such as nitinol or ultra-high molecular weight polyethylene (UHMWPE)suture material, or nylon. The suture, strap or band 220 is woventhrough the slots 216, 217 in the clamping member 210 and distal member,and attached to the tabs 254 of the superior member 250. The tabs 254are inserted through one of the slots 216, selected to control the forceapplied by superior member 250.

This embodiment of the device 250 can be placed on the patient whilefully assembled and then the suture, strap or band 220 tightened untilthe desired compression is reached. The mechanism provides a lockingfeature such that compression is not lost through repetitious motion.

In some embodiments, the means for locking also includes a release, orunloading, method in the event that the desired compression decreaseswith time.

Although FIG. 4 shows a suture, strap or band 220, in other embodimentsother mechanisms are substituted, such as, but not limited to:

a. Cable tie configurations

b. Enhanced hook and loop fastener for increased holding strength

c. Strap/buckle mating device

d. Super-elastic ribbon/Shape set to distances that providescompression, stretched to fit over surgical site and allowed to returnto its natural state providing the desired compression.

e. UHMWPE Suture with locking technology integrated in mating features

FIG. 5 shows an embodiment of a fixation device 300, comprising aproximal clamping member 310 and a distal clamping member 311. Each ofthe proximal and distal clamping members 310, 311 has an adjustableclamping collar 112 adapted to receive a digit 170 therethrough. Thedevice 300 of FIG. 5 can include any type of clamp 112 described abovewith respect to the device 100 of FIGS. 1-3, and solely for brevity,descriptions thereof are not repeated.

The device 300 has first and second coaxial helical members 322 and 324opposing each other. For example, in FIG. 5, from left to right, helicalmember 322 is wound in a clockwise direction around a longitudinal axisof the device 300, and helical member 324 is wound in acounter-clockwise direction around the longitudinal axis. Each of thehelical members 322, 324 has a respective proximal end fixedly attachedto the proximal clamping member 310 and a respective distal end fixedlyattached to the distal clamping member 311. In some embodiments, thehelical members 322, 324 are joined to the clamping members 310, 311 bybe laser-welded or other suitable technique. Each of the first andsecond coaxial helical members 322, 324 is in the form of helical bandhaving an inner support surface arranged to be wrapped around the digit170.

The helical members 322, 324 have spring-like material properties.Flexibility at the joint can be controlled by the stiffness in thematerial selection for the helical members. In some embodiments, thehelical members 322, 324 comprise spring steel or nitinol.

In use, the clamping members 310, 311 are positioned on opposing ends ofthe joint-line at the surgical/treatment site.

1. The user positions one clamp proximally with respect to the jointline. The user secures the proximal clamp 312 of member 310 to fix thelocation of device 300.

2. The user extends the free clamp 312 axially in the distal direction,stretching the helical members 322, 324 beyond their relaxed lengths.

3. The user secures the distal clamp 312 of member 311 in the extendedposition.

Once installed, the helical members 322, 324 react similar to anextension spring as they are strained in extension between two fixedmembers 310, 311. This results in active compression across the jointacting concurrently with the radial compression created by the clampingaction. Device 300 allows some flexion, but, selection of the diameterof the helical members 322, 324 allows the designer to limit the amountof flexion the device 300 affords.

FIGS. 6-11 show an embodiment of a fixation device 400, comprising aproximal clamping member 410 and a distal clamping member 411. Each ofthe proximal and distal clamping members 410, 411 has an adjustableclamping collar 112 (not shown in FIGS. 6-11) adapted to receive a digittherethrough. The device 400 of FIGS. 6-11 can include any type of clamp112 described above with respect to the device 100 of FIGS. 1-3, andsolely for brevity, descriptions thereof are not repeated.

Device 400 has a plurality of longitudinal spacers 420. Eachlongitudinal spacer 420 has a proximal end attached to the proximalclamping member 410 and a distal end attached to the distal clampingmember 411. Each longitudinal spacer 420 has at least one threaded end,and one of the proximal and distal clamping members 410, 411 has arespective thread configured to receive the threaded end for adjusting aseparation between the proximal and distal clamping members. In someembodiments, the clamping members have are countersunk to receive nuts422 for receiving the threads of the spacers 420 (See FIGS. 9 and 10).In some embodiments, spacers 420 are threaded throughout their lengths.In other embodiments, the spacers 420 are threaded at each end, and havea smooth surface in between, configured to receive a tighteninginstrument (e.g., a wrench) to adjust a distance between the proximaland distal clamping members 410, 411.

Device 400 has a plurality of spring members 430. Each spring member 430has a proximal end attached to the proximal clamping member 410 and adistal end attached to the distal clamping member 411. For example, asshown in FIG. 9, each end of each spring member 430 fits in a respectiveslot 412 of clamping members 410 and 411. Each spring member 430 islocated adjacent to and radially inward from a respective longitudinalspacer 420. Each longitudinal spacer 420 constrains its respectivespring member 430 to bow radially inwards.

In the embodiment of FIGS. 6-11, the plurality of longitudinal spacers420 includes four longitudinal spacers, and the plurality of springmembers 430 include four spring members arranged approximately evenlyaround a circumference of the proximal clamping member and distalclamping member. Other embodiments include different numbers of spacers420 and spring members 430 (e.g., 2 or 6).

The device 400 achieves radial compression. The adjustable clamps createa site of fixation on either side of the joint-line. Rotating thespacers 420, with their threaded ends, creates linear extension orretraction of the distance between the clamping members 410, 411.

When the spacers 420 are rotated to reduce the distance between theclamping member 410, 411, the spring members 430 bow and flex inwards asthe clamping members 410, 411 translate towards each other, creatingradial stability. Device 400 achieves simultaneous radial stability andaxial compression at the joint-line.

FIG. 11 shows the device 400 with a detachable drill guide 500detachably connected to the distal clamping member 411. The detachabledrill guide 500 has a guide portion 510 adapted to guide a drill along aproximal-distal axis should an intramedullary device be appropriate. Theguide portion 510 has a tapered lead in guide with an opening 512,through which the drill is inserted.

The drill guide 500 comprises a support structure including at least apair of radial arms 515, 517 and a longitudinal arm 516 for positioningthe guide portion 510 a variable distance away from the distal clampingmember 411. The radial arms 515, 517 and longitudinal arm 516 areextendible for varying a radial offset and a longitudinal displacementof the guide portion 510 relative to the distal clamping member 411.

Some embodiments provide fine-tuning and adjustable height and length toensure that the guide is in the desired location in both thelongitudinal and superior/inferior directions. Once the desired locationis determined, the adjustable arms lock into place. This achievesaccurate and consistent placement of temporary fixation devices orpre-drills. Various mechanisms can be used to provide adjustability. Forexample, in some embodiments, as shown in FIG. 11A, the drill guide 510and cylindrical body 520 are an assembly, wherein the cylindrical body520 replaces the post 515 of FIG. 11. The post 521 has detents 522 atpredetermined offsets from each other. The drill guide 510 has at leastone spring plunger 523 threaded into the cylindrical body 520perpendicular to the tapered guide 510. The spring plungers are biasedto engage the post detents, retaining the drill guide 510 in position &will disengage upon sufficient force supplied in the direction of thepost axis to allow positional adjustments of the drill guide. In anotherembodiment, as shown in FIG. 11B, the threaded post 531 is attached to arod 530 & drill guide 510 as an assembly. The longitudinal post 516 isattached to a threaded nut 532 in which the nut is constrained intranslation coaxially and perpendicular to the threaded axis. As thethreaded nut 532 is turned, the assembly comprising the threaded post531, rod 530 & drill guide 510 will move along the threaded body's axisper the threaded pitch. In other embodiments (not shown), the threadedpost 531 mates with a worm gear attached to the post 516. As the wormgear is turned the assembly comprising the threaded post 531, rod 530 &drill guide 510 will move along the threaded body's axis per thethreaded pitch.

The drill guide 500 has an attachment mechanism 520 which allows it tobe secured to one of the clamping members 411. In some embodiments, theattachment mechanism is a partial collar 520 which matches a portion ofthe distal clamping member 411. In other embodiments (not shown), theattachment mechanism is a complete ring, matching the shape of clampingmember 411.

Although the drill guide is only shown in FIG. 11, the drill guide canbe used with any of the devices 100, 200, or 300 described above.

The material of drill guide 500 can be comprised of either radiopaque orradiolucent materials. A radiolucent material (e.g., hard plastic orglass filed polymer) may be desired if the assembly is to be imaged byfluoroscopy in situ, and the physician does not want the drill guide toappear in the image. A physician may desire a radiopaque material ifhe/she wishes to establish the position of the drill guide 500 withrespect to the bone under fluoroscopy, for example.

FIGS. 12-15 show an embodiment of a fixation device 600 comprising atube 610 comprising a contractible tubular woven mesh configured tocontract radially under longitudinal tension. Such contractible tubularwoven meshes are commonly referred to as “Chinese finger traps,” and aredescribed, for example, in U.S. Pat. Nos. 2,783,758, 3,872,861 and5,649,541, which are incorporated by reference herein.

The contractible tubular woven mesh 610 has at least one helical yarn orfiber 630 fastened at or near a first end 611 of the tube 610 and wovenhelically through the mesh and extending from a second end 612 of thetube 610 opposite the first end 611 of the tube, such that the yarn 630is capable of applying radial compression to the tube when placed undertension. The helical yarn or fiber 630 is a separate yarn or fiber fromthose used to form the contractible tubular woven mesh 610. In someembodiments, the helix of the yarn or fiber 630 winds around thecircumference of the tube 610 with a different period that the fiberswhich constitute the mesh of tube 610. In some embodiments, the helicalyarn or fiber 630 comprises a different material from the material ofthe tube 610. The helical yarn or fiber provides a drawstring

In some embodiments, the at least one helical yarn or fiber 630 includestwo opposing yarns or fibers 630 extending in opposite directions arounda circumference of the tube 610. That is, one is configured as a righthand helix and the other is a left hand helix, so that viewed in adirection of the longitudinal axis of the tube 610, one helix windsclockwise around the tube, and the other helix winds counter-clockwisearound the tube. In some embodiments, the yarn or fiber 630 includes acircular winding (in a plane perpendicular to the longitudinal axis ofthe tube 610) at each end of the tube 610, so that pulling the stringcauses both radial compression and cinching of the ends of the tube 610.The helix crosses in the middle of the fixation device 600 such thatwhen cinched, the contraction of the helical yarn or fiber 630 causes abent joint to straighten through the application of a compressive forcealong the helix.

The device 600 is slipped over the digit to be treated, and the at leastone helical yarn or fiber 630 is (are) pulled and tied or fastened. Theat least one helical yarn or fiber 630 act as a drawstring, cinching thetube 610 and placing the tube in radial compression. In someembodiments, the device 600 is used to straighten the digit (e.g., toe)for percutaneous drilling into the end of the toe. The mesh willcompress the toe while holding it rigid in line for drilling. Thisdevice 600 can also be used for minor adjustment until the soft tissuereleases.

In some embodiments, the user attaches a weight to the yarns or fibers630 to maintain compression during a surgical procedure. In otherembodiments, the device 600 is used to provide stability post-surgeryfor a length of time by pulling, cinching and tying off the helicalyarns or fibers 630. The device 600 can provide compression and helpcorrect deformity.

In some embodiments, the device 600 is used alone to provide compressionand support. In some embodiments, additional support and rigidity isprovided by inclusion of optional sleeves 620. In some embodiments, aplurality of sleeves 620 are arranged around an outer surface of thetube 610. The sleeves 620 are substantially smaller in diameter than thetube 610. Any number of sleeves 620 may be included. In someembodiments, four, six or eight sleeves 620 are uniformly distributedabout the circumference of the tube 610. In some embodiments, thesleeves 620 comprise the same material as the mesh of tube 610. In otherembodiments, the sleeves comprise a different material from tube 610.

Each of the plurality of sleeves 620 has a respective first end fixed ator proximate to a first end 611 of the tube 610 and a respective secondend fixed at or proximate to a second end 612 of the tube 610 oppositethe first end 611. Each sleeve 620 has a portion that is freely movablerelative to the tube 610, the portion being between the first end andsecond end of each sleeve. In some embodiments, the sleeves are onlyfixed (e.g., by sewing) at their ends to the respective ends 611, 612 ofthe tube 610, and the sleeves are free to move relative to the tube atall intermediate locations along the lengths of the sleeves. In otherembodiments, the sleeves 620 are fixed at both ends and at one or moreintermediate points along their length to the outer surface of the tube610. In other embodiments, the sleeves 620 are sewn at or near one endof the tube 620, and the other end of each sleeve 620 is free to moverelative to the tube 610.

In some embodiments, the user can optionally insert at least oneremovably insertable rib 622 in at least a respective one of theplurality of sleeves 620. In some embodiments, the ribs are insertedafter pulling the helical yarns or fibers 630 to cinch the tube 610. Theat least one rib 622 is formed of a material that is more rigid than amaterial of the tubular woven mesh. The rib can comprise any of avariety of materials, such as wood, plastic or a more rigid material.

FIG. 15 shows the device 600 after the user inserts six ribs 622 in therespective sleeves 620. The physician can determine on an individualbasis how many ribs to insert, if any, and where to put the ribs toachieve desired rigidity in a directional manner. Thus, the physiciancan select placements of the ribs to increase rigidity in thelateral-medial direction, or in the superior-ventral direction.

FIGS. 12-15 show an embodiment of device 600 having both the helicalyarns or fibers 630 and the sleeves 620. In other embodiments, thedevice includes a tube 610 with the sleeves 620, but without the helicalyarns or fibers 630. In other embodiments, as shown in FIGS. 15A-15C,the device 650 includes a tube 610 with the helical yarns or fibers 630,but without the sleeves 620. When cinched, the helical yarns or fibers630 causes a bent joint of digit 170 to straighten through theapplication of a compressive force along the helix.

Although FIGS. 12-15C show the device 600 used alone, the device 600 canbe used in combination with any of the devices shown in FIGS. 1-11. Inparticular, in some embodiments, the device 300 (FIG. 5) or 400 (FIGS.6-11) can be applied over the device 600. The physician applies device600 and cinches the helical yarns or fibers 630, and optionally insertsone or more ribs 622 in sleeves 620. Then the physician places thedevice 300 or 400 over the digit and tightens the clamps 312 or 112 ateach end of the device 300 or 400. The physician attaches the drillguide 500 and performs the drilling (e.g., for K-wire insertion). Thisis just one example, and the device 600 can be used with other externalfixation devices to provide compression and support during surgicalprocedures.

FIGS. 16-19 show an embodiment of a bone implant 700 suitable forcorrecting a deformity such as a hammertoe. This device 700 addressesthe common secondary procedure stabilize the metatarsophalangeal (MTP)joint by releasing the joint capsule and employing a temporary fixationwire. The bone implant 700 comprises a helical threaded member 710having first and second ends 704, 706 and a longitudinal central opening708 extending from the first end 704 to the second end 706. Thelongitudinal central opening has a longitudinal axis 702.

At least one blade 720 integrally attached to the first end 704 of thehelical threaded member 710. The blade 720 extends in a radial directionaway from the longitudinal axis 702. The blade 720 has an outer edgewith a plurality of teeth thereon 722. The blade 720 has an outer edgewith a plurality of teeth thereon 722. In some embodiments, as shown inFIGS. 16-19, the implant 700 has two blades evenly spaced andsymmetrically arranged to extend in opposite radial directions away fromthe longitudinal axis 702. A central tube 730 with a central cannula 732runs along the central axis for a portion of the length of the helicalthreaded member.

In some embodiments, as shown in FIGS. 16-19, the helical threadedmember 710 has a cork-screw shape. The central longitudinal opening(referred to herein as a cannula) of the helical threaded member 710 isopen to the exterior of the device. The central opening 708 iscontinuous with the cannula 732 of the central tube 730 and the cannula724 which extends to the end of blades 720. This configuration isanalogous to a cannula diameter greater than the minor diameter of ascrew. The cork screw configuration allows implantation over a k-wire,which is used to address metatarsophalangeal (MTP) joint soft-tissuecontracture. The cork-screw configuration of helical threaded member 710allows both axial compression (FIG. 17) and extension (FIG. 18) andperpendicular bending flexion (FIG. 19), similar to the range of motionof a coiled spring. This provides additional flexibility in the joint aswell as enhanced bone integration within the threads of the helicalthreaded member 710. The degree of flexibility is a function of materialproperties and geometry and can be controlled and optimized.

In some embodiments, implant 700 comprises a material havingsuper-elastic material properties, such as nitinol. In otherembodiments, the material is selected to include shape memoryproperties. Shape memory alloys, such as Nickel Titanium (nitinol),undergo a phase transformation in their crystal structure when cooledfrom the stronger, high temperature form (Austenite) to the weaker, lowtemperature form (Martensite). When heated after deformation, the shapememory material recovers its original shape. For example, an implant 700formed of a material with shape memory is set in the expanded state(FIG. 18), and implanted. Then the device 700 compresses when introducedinto the body due to temperature increase (FIG. 17). This ensurescompression at the joint while maintaining some flexibility. Also,nitinol exhibits superelasticity if deformed in an environment abovetheir transformation temperatures and will change phase from austeniteto stress-induced martensite, allowing it to be strained from ˜2-6% withnearly constant stress & return from martensite to austenite duringunloading.

In the configuration as shown, the cantilevered blades 720 deflectinwards when radial force is applied, allowing compatibility with anundersized preparation hole. When inserted in the bone, the cantileverblades 720 flex outward increasing fixation in the bone. The outwardspring force of the blades 720 is a function of the material propertiesand geometry, and can be controlled and optimized.

FIG. 20 shows an embodiment of a device 800 which is similar to thedevice 700 of FIGS. 16-19, except that a single blade 820 with teeth 822is provided. The bone implant 800 comprises a helical threaded member810 having first and second ends 804, 806 and a longitudinal centralopening 808 extending from the first end 804 to the second end 806.Device 800 is partially cannulated, providing greater flexibility alongthe helical threaded member 810, along the axis 802 from the first end804 to the second end 806. Compared to the device 700, the single bladeconfiguration of blade 820 provides greater rigidity when inserted inthe bone. In some embodiments, the device 800 comprises a superelastic,shape memory alloy, such as nitinol, providing the expansion/contractionproperties of the device 700, but with greater rigidity.

FIG. 21 shows an embodiment of a partially cannulated device 900 whichis similar to the device 800 of FIG. 20, except that four perpendicularblades 920 with teeth 922 are provided in a continuous, cross-bladeconfiguration. The bone implant 900 comprises a helical threaded member910 having first and second ends 904, 906 and a longitudinal centralopening 908 extending from the first end 904 to the second end 906.Compared to the devices 700 and 800, the cross-blade configuration ofblades 920 provides greater rigidity when inserted in the bone. Thecross-blade configuration can provide a greater degree of fixation. Thecross-blade configuration allows implant pre-drill (circular)preparation instead of broaching. Using an undersized pre-drill step,the crossed blades 920 achieve fixation by circumferential interferencewith the surrounding bone. In some embodiments, the device 900 comprisesa superelastic shape memory alloy, such as nitinol, providing theexpansion/contraction properties of the device 700 described above butwith greater rigidity & fixation

FIG. 22 shows an embodiment of a fully cannulated device 1000 which issimilar to the device 700 of FIGS. 16-20, except that four perpendicularblades 1020 are provided in a cross-blade configuration, evenly spacedaround the longitudinal axis. The central opening 1008 is continuouswith the cannula (not shown in FIG. 22) of the central tube 1030 and thecannula 1024 which extends to the end of blades 1020. A K-wire or thelike can be placed through the central opening 1008 of helical threadedmember 1010, along the axis 1002 from the first end 1004 to the secondend 1006. Compared to the device 700, the four blade configuration ofblades 1020 can provide a greater degree of fixation. The cross-bladeconfiguration allows implant pre-drill (circular) preparation instead ofbroaching. Using an undersized pre-drill step, the crossed blades 1020achieve fixation by circumferential interference with the surroundingbone. In the configuration of FIG. 22, the four cantilevered blades 1020deflect inwards when radial force is applied, allowing compatibilitywith an undersized preparation hole. When inserted in the bone, thecantilever blades 1020 flex outward increasing fixation in the bone. Theoutward spring force of the blades 1020 is a function of the materialproperties and geometry, and can be controlled and optimized. In someembodiments, the device 1000 comprises a superelastic, shape memoryalloy, such as nitinol.

FIGS. 23 and 24 show an embodiment of a fully cannulated implant 1100which is similar to the device 1000 of FIG. 22, except that the helicalthreaded member 1110 of implant 1100 has a minor diameter larger than adiameter of the longitudinal central opening 1124, so that the helicalthreaded member 1110 has a central tube 1140 with a continuous innersurface 1142 around the longitudinal central opening (cannula) 1124. Inimplant 1100, four perpendicular blades 1120 with teeth 1122 areprovided in a cross-blade configuration, evenly spaced around thelongitudinal axis 1102. In other embodiments, only two cantilever blades(similar to blades 720 in FIG. 16) are provided, but the rest of theimplant 1100 is otherwise the same. In some embodiments, the device 1000comprises a superelastic, shape memory alloy, such as nitinol.

A K-wire or the like can be placed through the central opening 1124 ofhelical threaded member 1110, along the axis 1102 from the first end1104 to the second end 1106. Compared to the device 700, the four bladeconfiguration of blades 1120 can provide a greater degree of fixation.The cross-blade configuration allows implant pre-drill (circular)preparation instead of broaching. Using an undersized pre-drill step,the crossed blades 1120 achieve fixation by circumferential interferencewith the surrounding bone.

FIGS. 25-29 show a method for installing the implant 1100. The samesequence of steps is performed for any of the fully cannulated implants,such as implant 700 (FIG. 16), and implant 1000 (FIG. 22). Note that inthe views of FIGS. 25-27, the proximal direction is left and the distaldirection is right, but in the views of FIGS. 28 and 29, the proximaldirection is right and the distal direction is left

In FIG. 25, the proximal bone (phalanx) 2503 is pre-drilled to receivethe K-wire 1126, and the physician broaches the middle phalanx 2502.

Then, the physician drills distally through middle phalanx 2502 andthrough the tip of the toe 2501 with the K-wire 1126, as shown in FIG.26.

Once the K-wire is exposed, a drill 2510 (shown in FIG. 27) is attachedto the distal end of the K-wire 1126. The K-wire 1126 is backed outtowards the distal end of the bone 2501, until the proximal tip of theK-wire 1126 is sub-flush with the joint line (i.e., withdrawn past theproximal end of middle phalanx 2502. In some embodiments, the K-wire isdrawn past the end of the middle phalanx 2502 by a distance greater thana length of the blades 1120.)

The helical threaded portion 1110 of the implant 1100 is then advancedinto the proximal phalanx 2503 until the implant 1100 is fully seated.Once the implant 1100 is fully seated, the physician closes the joint,forcing the blades 1120 into the previously broached canal as shown inFIG. 28.

With a correctly aligned joint (optionally using one of the externalfixation devices shown in FIGS. 1-15), the physician advances the K-wire1126 in the proximal direction, through the cannulated implant 1100 intothe MP joint. They physician caps the K-wire 1126 with a Jurgan ball1128, completing the installation.

FIGS. 30-34 show a bone implant 1200 comprising a central shaft 1210having first and second ends and a longitudinal axis. A first set ofblades 1220 are integrally attached to the first end of the centralshaft 1210. The first set of blades 1220 extends in a radial directionaway from the central shaft 1210. Each of the first set of blades 1220has an outer edge with a plurality of teeth 1222 thereon.

A second set of blades 1250 with teeth 1252 are integrally attached tothe second end of the central shaft 1210. The second set of blades 1250extend in the radial direction away from the central shaft 1210. Each ofthe second set of blades 1250 has an outer edge with a plurality ofteeth 1222 thereon. The second set of blades are rotationally offsetfrom the first set of blades.

In some embodiments, each one of the second set of blades 1250 isrotationally spaced midway between an adjacent pair of the first set ofblades 1210. For example, in the implant of FIGS. 30-34, there are fourfirst blades 1220 and four second blades 1250. The angular spacingbetween each second blade 1250 and the adjacent first blades 1210 oneither side is 45 degrees. FIGS. 31 and 32 show the angular offsetsbetween the two sets of blades 1220, 1250.

In some embodiments, the bone implant 1200 has a cannula 1224 extendingalong the longitudinal axis 1202 from a first end of the bone implant toa second end of the bone implant. In other embodiments, the implant issolid, with no cannula. In some embodiments, the device 1000 comprises asuperelastic, shape memory alloy, such as nitinol.

In some embodiments, an instrument is provided that inserts a broach inthe bone on one side of the joint in a first orientation, and then isrotated +/−45 degrees to broach the bone on the other side of the jointin a second orientation rotationally offset from the first orientation.The instrument has a shape to match the cross-blade configuration 1220of the implant 1200. In other embodiments, a K-wire channel ispre-drilled into the bone prior to inserting the implant, and no broachis required. In either case, the physician uses a safety tool to handlethe implant 1200. The safety tool has a gripping handle and a headshaped to receive either the blades 1220 or the blades 1250, so thephysician is not harmed by the blades 1220, 1250.

The inventors have determined that one of the sources of problems inhammertoe implants is implant loosening after insertion. The rotationaloffset between blades 1220 and blades 1250 provides a differentorientation on the distal end and the proximal end to help preventagainst the blades from loosening.

FIGS. 33-34 show the method of insertion. First, the bones 2501-2503 arepre-drilled as shown and described above with reference to FIGS. 25-27,and the physician inserts the K-wire 1126 across the joint. Thealignment may be checked by fluoroscopy to confirm where to insert theimplant. The K-wire 1126 is backed out beyond the proximal end of themiddle phalanx 2502.

As shown in FIG. 33, the physician inserts the blades 1220 of implant1200 in the proximal phalanx 2503, where the K-wire pre-drilled hole isvisible. The physician can use the above-mentioned safety tool for thispurpose.

Then as shown in FIG. 34, the physician takes the PIP joint and placesthe broached or pre-drilled side of the middle phalanx 2502 over theblades 1250 and presses the middle phalanx into place, with the implantnow embedded in both the middle phalanx 2502 and the proximal phalanx2503.

If the implant 1200 is cannulated, then the K-wire 1126 is advancedthrough the implant in the same manner described above with reference toFIG. 29, and a Jurgan ball 1128 is attached.

Although the subject matter has been described in terms of exemplaryembodiments, it is not limited thereto. Rather, the appended claimsshould be construed broadly, to include other variants and embodiments,which may be made by those skilled in the art.

What is claimed is:
 1. A fixation device, comprising: a first clampingmember having an adjustable clamping collar and a first curved supportportion attached to the adjustable clamping collar, the first clampingmember adapted to receive a digit therethrough, the first curved supportportion adapted to support an inferior surface of a proximal phalanx ofthe digit; a distal member adjustably attachable to the first clampingmember, the distal member having a second curved support surface adaptedto support an inferior surface of a distal phalanx of the digit and acurved distal end adapted to apply a compressive force in a proximaldirection to a distal end of the distal phalanx.
 2. The fixation deviceof claim 1, further comprising a superior member configured to beattached to the first clamping member and the distal member, thesuperior member having a curved surface adapted to apply a force againsta superior surface of the digit.
 3. The fixation device of claim 2,wherein the superior member has one of the group consisting of a slotand a locking tab, and at least one of the first clamping member and thedistal member have the other of the group consisting of a slot and alocking tab for engaging the slot or locking tab of the superior member.4. The fixation device of claim 2, further comprising means for lockingthe superior member to the first clamping member and the distal memberwherein the superior member includes at least one locking tab, and atleast one of the first clamping member and the distal member includes aplurality of slots, each respective slot configured to receive the atleast one locking tab at a respectively different location relative tothe first clamping member and the distal member, for applying arespectively different compressive force in an inferior direction. 5.The fixation device of claim 1, wherein one of the first clamping memberand the distal member includes at least one locking tab, and the otherof the first clamping member and the distal member includes a pluralityof slots, each respective slot configured to receive the at least onelocking tab with the distal member at a respectively different locationrelative to the proximal member, for applying a respectively differentcompressive force in the proximal direction.
 6. A fixation device,comprising: a proximal clamping member and a distal clamping member,each of the proximal and distal clamping members having an adjustableclamping collar adapted to receive a digit therethrough; first andsecond coaxial helical members opposing each other, each of the helicalmembers having a respective proximal end fixedly attached to theproximal clamping member and a respective distal end fixedly attached tothe distal clamping member.
 7. The fixation device of claim 6, whereineach of the first and second coaxial helical members is in the form ofhelical band having an inner support surface arranged to be wrappedaround the digit to compress a joint of the digit.
 8. A fixation device,comprising: a proximal clamping member and a distal clamping member,each of the proximal and distal clamping members having an adjustableclamping collar adapted to receive a digit therethrough; a plurality oflongitudinal spacers, each having a proximal end attached to theproximal clamping member and a distal end attached to the distalclamping member; a plurality of spring members, each spring memberhaving a proximal end attached to the proximal clamping member and adistal end attached to the distal clamping member, each spring memberlocated adjacent to and radially inward from a respective longitudinalspacer, each longitudinal spacer constraining its respective springmember to bow radially inwards.
 9. The fixation device of claim 8,wherein each longitudinal spacer has at least one threaded end and oneof the proximal and distal clamping members has a respective threadconfigured to receive the threaded end for adjusting a separationbetween the proximal and distal clamping members.
 10. The fixationdevice of claim 8, wherein the plurality of longitudinal spacersincludes at least four longitudinal spacers, and the plurality of springmembers include at least four spring members arranged approximatelyevenly around a circumference of the proximal clamping member and distalclamping member.
 11. The fixation device of claim 8, further comprisinga detachable drill guide detachably connected to the distal clampingmember, the detachable drill guide having a guide portion adapted toguide a drill along a proximal-distal axis.
 12. The fixation device ofclaim 11, wherein the drill guide comprises a support structurecomprising at least a pair of radial arms and a longitudinal arm forpositioning the guide portion a variable distance away from the distalclamping member.
 13. The fixation device of claim 12, wherein the radialarms and longitudinal arm are extendible for varying a radial offset anda longitudinal displacement of the guide portion relative to the distalclamping member.
 14. A fixation device, comprising: a tube comprising acontractible tubular woven mesh configured to contract radially underlongitudinal tension; and at least one helical yarn or fiber fastened ator near a first end of the tube and woven helically through the mesh andextending from a second end of the tube opposite the first end of thetube, such that the yarn is capable of applying radial compression tothe tube when placed under tension.
 15. The fixation device of claim 14,wherein the at least one helical yarn or fiber includes two opposingyarns or fibers extending in opposite directions around a circumferenceof the tube, such that the helical yarn or fiber is configured to cinchends of the tube while applying compressive force to straighten a jointof a digit surrounded by the tube, when the helical yarn or fiber ispulled.
 16. The fixation device of claim 14, further comprising: aplurality of sleeves arranged around an outer surface of the tube, thesleeves smaller in diameter than the tube; and at least one ribremovably insertable in at least a respective one of the plurality ofsleeves, the at least one rib formed of a material that is more rigidthan a material of the tubular woven mesh.
 17. A fixation device,comprising: a tube comprising a contractible tubular woven meshconfigured to contract radially under longitudinal tension; a pluralityof sleeves arranged around an outer surface of the tube, the sleevessmaller in diameter than the tube; and at least one rib removablyinsertable in at least a respective one of the plurality of sleeves, theat least one rib formed of a material that is more rigid than a materialof the tubular woven mesh.
 18. The fixation device of claim 17, whereineach of the plurality of sleeves has a respective first end fixed at orproximate to a first end of the tube and a respective second end fixedat or proximate to a second end of the tube opposite the first end, eachsleeve having a portion that is freely movable relative to the tube, theportion being between the first end and second end of each sleeve.
 19. Abone implant comprising: a helical threaded member having first andsecond ends and a longitudinal central opening extending from the firstend to the second end, the longitudinal central opening having alongitudinal axis; and at least one blade integrally attached to thefirst end of the helical threaded member, the blade extending in aradial direction away from the longitudinal axis, the blade having anouter edge with a plurality of teeth thereon.
 20. The bone implant ofclaim 19, wherein the helical threaded member has a minor diameterlarger than a diameter of the longitudinal central opening, so that thehelical threaded member has a continuous inner surface around thelongitudinal central opening.
 21. The bone implant of claim 19, whereinthe helical threaded member has a cork-screw shape.
 22. The bone implantof claim 19, wherein the at least one blade includes two or four bladesevenly spaced around the longitudinal axis.
 23. The bone implant ofclaim 19, wherein the longitudinal central opening extends to an end ofthe at least one blade opposite the helical threaded member.
 24. A boneimplant comprising: a central shaft having first and second ends and alongitudinal axis; and a first set of blades integrally attached to thefirst end of the central shaft, the first set of blades extending in aradial direction away from the central shaft, each of the first set ofblades having an outer edge with a plurality of teeth thereon; and asecond set of blades integrally attached to the second end of thecentral shaft, the second set of blades extending in the radialdirection away from the central shaft, each of the second set of bladeshaving an outer edge with a plurality of teeth thereon, the second setof blades rotationally offset from the first set of blades.
 25. The boneimplant of claim 24, wherein each one of the second set of blades isrotationally spaced midway between an adjacent pair of the first set ofblades.
 26. The bone implant of claim 24, wherein the bone implant has acannula extending along the longitudinal axis from a first end of thebone implant to a second end of the bone implant.
 27. The bone implantof claim 19, wherein the bone implant comprises a shape memory alloy.28. The bone implant of claim 19, wherein the bone implant comprises asuperelastic alloy.
 29. The bone implant of claim 19, wherein the boneimplant comprises nitinol.